The broad, long-term objective of this research is to understand age-related changes in auditory and vestibular modalities in health and disease. Much is known about auditory aging, relatively little about vestibular aging and even less comparing the two systems. We hypothesize that functional aging of one inner ear sensory system does not obligate change in the other and genetic background and/or gender may influence vestibular and auditory aging. The proposed work will test these hypotheses using inbred mouse strains. Specific aim 1 will characterize age related changes in auditory and vestibular function and will compare the changes between the two sensory systems across the lifespan in 4 strains with different genetic backgrounds. We will record distortion product otoacoustic emissions (DPOAEs), auditory brainstem responses (ABR), and vestibular evoked potentials (VsEP) at monthly ages from 2 to 18 months. Specific aim 2 will compare inner ear functional aging between males and females. This work will lead to a better understanding of inner ear aging and predisposing factors (genetic and gender) for age related changes in vestibular and auditory function. The work will form the fundamental basis for future studies of anatomical or molecular correlates for inner ear aging and peripheral influences on aging of the central nervous system. Ultimately, the work may lead to better diagnosis and treatment of age related hearing loss and dizziness. [unreadable] [unreadable] [unreadable]